The present invention relates to an enclosure for electronics suitable for use in a hostile environment, and, more particularly, to a sealed electronic enclosure including a printed circuit board as a structural element.
Complex electronic systems which control the engine, fuel system, braking, and steering systems of vehicles are increasingly common in control systems of motor vehicles. For logistical reasons, electronic systems of this type are typically stored in the engine compartment of the vehicle, in reasonably close proximity to the systems which they control. This configuration assures that wiring of the components is relatively easy and that leads are relatively short. While positioning of the electronic components in the engine compartment is convenient, however, there are a number of problems associated with storing electrical circuitry in this environment. In particular, the engine compartment is open to hostile environmental conditions including salt spray, wetness, high humidity, and temperature extremes which can be problematic for electronic circuitry. Electronic circuitry, therefore, is prone to premature failure when stored under these conditions.
To protect the electronic components from hostile weather and temperature conditions, electronic components and circuit boards are typically stored in an enclosure constructed from a moisture-resistant material. Connections to the external environment are made through holes in the enclosure through which individual wires can be routed, or in which connectors to the internal circuitry are mounted. The individual wires and/or connectors are typically mounted on a circuit board, which is mounted behind a wall of the enclosure. The circuit board is sealed to the wall of the enclosure using a number of sealing devices including rubber gaskets positioned between the board and the wall of the enclosure, and silicone sealants provided between each of the connectors on the printed circuit board and the wall of the enclosure. The gaskets and other sealants are provided to prevent moisture from entering the enclosure through the interface between the board and the enclosure walls, and through holes in the board. This would be required with any type of standard cover.
While electronic enclosures of this type are generally effective for protecting the enclosed electronic circuitry, these enclosures add unnecessary parts, manufacturing costs and complexity. For example, to properly provide a seal between the underlying board and the enclosure, the silicone sealants must be added after the board is mounted to the wall of the enclosure. Sealing is therefore a difficult, labor intensive and time consuming process. Further, even when done carefully, sealants added between assembled components vary significantly in quality from part-to-part and often provide an insufficient seal to prevent moisture leakage. Additionally, positioning and tightening a gasket in place between the printed circuit board and the wall of the enclosure can also be difficult when the enclosure is assembled in this way, particularly since the gasket is often positioned where it cannot be readily seen during assembly. There remains a need, therefore, for an enclosure for electronic equipment which is moisture-resistant, and both inexpensive and easy to manufacture.
The present invention is an enclosure for electronic circuitry comprising a container which defines a volume for housing the electronic circuitry and having an opening therein for communicating with the surrounding environment; a printed circuit board mounted to the container and covering the opening to the circuitry and sealing it off from the surrounding environment; a first electrical connector mounted to the inside surface of the printed circuit board to provide an electrical connection with the enclosed electronic circuitry; a second electrical connector mounted to the outside surface of the printed circuit board to provide electrical connections to external circuitry; and wherein the printed circuit board includes conductors that electrically connect the first and second electrical connectors.
A general object of the invention is to provide an inexpensive enclosure for electronic circuitry which protects the circuitry from the environment. By covering the open end of the enclosure with a printed circuit board having connectors on both sides, the electronic circuitry can be electrically connected to external circuits without the need for separate sealed openings that can leak and may require additional manufacturing steps.